Process for driving anchoring devices into a base using a propellant composition of pentaerythritol tetrani-trate and tetrazol-azo-amino-guanidine



United States Patent Ofitice 3,336,837 Patented Aug. 22, 1967 3,336,837PROCESS FOR DRIVING ANCHORING DEVICES INTO A BASE USING A PROPELLANTCOMPO- SITION OF PENTAERYTHRITOL T E T R A N I- TRATE AN DTETRAZOL-AZO-AMlNO-GUANI- DINE Vinzenz Anger, Technergasse 35, Vienna,Austria N Drawing. Filed Apr. 21, 1965, Ser. No. 449,889 3 Claims. (Cl.89-1) ABSTRACT OF THE DISCLOSURE A process for driving anchoring devicesby a tool in which a deflagrating propellant composition in pellet formis ignited by percussion to drive the anchoring devices. The propellantcomposition consists essentially of a mixture of pentrite andtetrazol-azo-amino-guanidine, the latter being present in an amountbetween and 30% by weight of the composition.

The present invention relates to processes for driving anchoring meansor fastening devices by the use of boltsetting tools, and to propellantcompositions for effecting such a process. In order to drive anchoringmeans, such as bolts and the like, into solid and strong materials, itis known in the art to use bolt-setting tools, where the driving energyis produced by the gases of combustion of an ignited powder charge. Ingeneral, cartridges have been used, which are charged with comparativelyslowly burning or deflagrating charges.

The defiagrating propellants generally used are gelatinized gun-cotton,and in some cases, black powder. The propelling composition is arrangedin a cartridge and its defiagration is caused by an initial igniterdevice or fuse, which contains, for example, fulminate of mercury, leadazide, di-azo-dinitrophenol, and similar substances.

Another groups of substances consists of highly explosive explosives,such as trinitroglycerin, pentaerythritol tetranitrate, trinitrotoluene,picric acid, hexanitro mannitol, and the like, which cannot be used forpropelling compositions owing to their explosive detonation. Detonationof such highly explosive materials is initiated by an initial igniter orfuse, i.e. substantially by the same igniting agents which are also usedfor deflagrating propellants. German Patent 289,017 has disclosed suchpriming or detonating compositions which contain an active ingredient,as for example, tetrazen. It is further known, for example, from GermanPatent 518,885, to use as a priming agent, lead trinitro resorcinate,the ignitibility of which is increased very substantially by smalladditions of A to less than 5% tetrazen. Even small amounts of tetrazenresult in an appreciable increase in ignitibility.

Recent investigations have shown that explosives having a nitric acidderivative base, which contain as a priming agent, in mixture, /4 toless than 5% tetrazen, demonstrate an explosive reaction course uponignition.

For example, if a mixture is prepared of 98% pentrite and 2% tetrazen,and if the same is granulated with acetone and in known manner is formedinto pellets having a diameter of 6 mm. and a weight of 0.1 to 0.3 g.,it is found that detonation actually occurs upon the percussion primingof said pellets. This is especially apparent if the pellet is used as apropellant in a bolt-setting tool of usual construction in which apropelling composition, in the form of cartridges, is generally employedand is caused to ignite by the blow of a hammer on a riveting set ordie. In the case under consideration, the chamber of the bolt-settingapparatus in which the pellet was accommodated was widened to such anextent that a jamming occurred.

It is an object of the invention to provide a composition which isignited upon percussion and burns in deflagrating manner for use in abolt-setting tool as a propellant for bolts or the like without causingany damage or distortion of the tool.

It is a further object of the invention to provide a composition of thetype set forth above which is completely combustible and which leavessubstantially no residue.

It is still a further object of the invention to provide the abovecomposition in the form of self-contained pellets. Moreover, suchpellets may be of graduated size for obtaining controlled bolt drivingeffects.

It is yet another object of the invention to stabilize an explosivenitric acid derivative to enable the latter to be burned in defiagratingmanner and by percussion ignition.

The present invention is particularly directed to a process for thedriving of anchoring or fastening means into solid and strong materialsby means of power operated bolt-setting tools, wherein, according to theinvention, propelling compositions, specifically in the form of pelletswhich burn in defiagrating manner, are ignited by percussion withoutrequiring the use of special igniting agents.

In order to effect such process, it is preferable to use shaped ormolded propelling compositions which contain highly explosive explosivesof the above-mentioned kind intimately mixed with an amount of tetrazensbetween 5 to 30 percent by weight, and preferably from about 10 to about20 percent by weight of the tetrazens in relation to the entirecomposition of nitric acid derivative and tetrazen. Upon ignition, saidpropelling compositions surprisingly do not exhibit detonation, butrather, undergo defiagration. Accordingly, the present invention furtherrelates to the preparation of a propelling compo sition withdeflagrating characteristics for use in boltsetting tools, saidpreparation containing the explosive material and a tetrazen compound inthe quantitative ratio indicated above.

It has further been found that, upon carrying out the process accordingto the invention, more particularly upon using propelling compositionsof the above-mentioned kind, a burning substantially free of residue isinsured within the above-mentioned mixing ranges and that, althoughtetrazen is known as an igniting agent decomposing without residue,tetrazen contents of, for example, 40% cause the formation ofperceptible combus' tion residues and are, at the same time, aconsiderable olfactory irritant. Depending on the kind and on thequantitative ratio of the respective mixing components, the tetrazensapparently exhibit different kinds of behavior which are unpredictable.Without having to accept any disadvantages, the propelling compositionpreparation according to the invention can be manufactured in any mannerdesired and may be prepared in the form of powders, granulates, jellies,plastic compounds, tablets, or other similar commercially availableforms. It is understood that the propelling composition preparationsaccording to the invention can be used in any form or shape desired,although another advantage of the propelling compositions according tothe invention resides precisely in the fact that they can be usedwithout cartridge cases, as for example, in the form of pellets.

It is understood that envelopes or casings may be pro vided, if desired,which burn practically without residue under the deflagrating reactionconditions of the propelling composition. For example, suitable coveringor coating agents may be nitrocellulose lacquers or organic, possiblynitrated, film-forming, monomeric or polymeric compounds, such asparaffins, hard gelatin, natural and/or synthetic waxes or resins,plastics and similar compounds which are known per se and can beselected readily by those skilled in the art.

Especially good results are obtained with pellets in the form oftablets. With or without the use of conventional pelleting or tabletingsubstances, it is possible to use the methods and apparatus generallyemployed for this purpose for producing such shaped or molded bodies,more particularly, shaped bodies weighing from 50 to 400 mg., andpreferably from 80 to 250 mg. Such pellets have in most cases a diameterranging from about 3 mm. to about 8 mm., and preferably from about 5 to6 mm.

The composition preparations according to the invention are formed to beparticularly favorable insofar that no corrosion phenomena could beobserved when they were used.

As regards technical dependability and safety, it is of essentialimportance for carrying out the present process that the propellingcompositions be ignited by percussion only and that they burn withoutexplosion or detonation upon flame ignition. With a view to improvingthe ignitibility, it is advantageous to place the percussion die notdirectly on the pellet, but to strike the pellet with a die havingfinite velocity. The difficult flammability of the propellingcompositions at temperatures in excess of about 600 C. also is eflectiveto counteract accidents.

Another appreciable advantage resides in the ready availability of thesubstances of the propelling composition as well as the possibility oftheir use without a cartridge case.

The tetrazen compound contained in the propelling compositionpreparations according to the invention is advantageouslytetrazol-azo-amino-guanidine. Within the scope of the mixture limitsindicated above, proportions of about 8 to percent by weight were foundto be most advantageous.

There shall now be described by way of example, a propelling compositionpreparation according to the invention, including the manufacturethereof.

Example 85% by weight pentrite and 15% by weight tetrazen, both inpowder form were intimately mixed in a heating dish and were granulatedby the addition of acetone. A usual commercial tableting or pelletingpress was used to press the resultant powdery mixture in the form ofpellets having a diameter of 6 mm. and a weight from 0.1 to 0.3 g. Thesepellets were used as propellants in a boltsetting tool, in whichnormally cartridges of different strength were ignited by the blow of ahammer on the riveting die. Instead of said cartridges, theabovedescribed pellets were used and the function of the tool with saidpropellant pellets was examined to determine the usability of saidpropellant.

The following factors were considered:

(a) Ignitibility.-The ignition of the pellet by the percussion of theriveting die occurs in dependable manner for all pellets ignited;

(b) Progress of the reaction.-Defiagrating consumption was observedduring the ignition, and the pellet is burned without residue. Theirritating odor caused by the produced smoke and gases, etc., was lessthan in the cartridges normally used;

(c) Eficiency (determined by the depth of penetration in a common base 0the driven bolt).The powder developed by the pellets of the inventioncorrespond to that of the commercially available cartridges. By usingpellets of different weights, it is possible to gradate the driving tothat obtained by different strength cartridges.

Numerous modifications and variations of the disclosed compositions andprocesses will be apparent to those skilled in the art without departingfrom the spirit and scope of the invention as defined in the attachedclaims.

What is claimed is:

1. In a process for driving anchoring devices by a tool, the stepscomprising igniting a propellant composition which is defiagrating andwhich is in pellet form to drive the anchoring devices, the ignitingbeing obtained by percussion, the propellant composition consistingessentially of a mixture of pentaerythritol tetranitrate andtetrazolazo-amino-guanidine, the latter being present in an amountbetween 5 and 30% by weight of the composition.

2. In the process as claimed in claim 1 wherein thetetrazol-azo-amino-guanidine is present in an amount of 15% by weight.

3. In the process as claimed in claim 1 wherein theterazol-azo-amino-guanidine is present in an amount 10 to 20% by weight.

References Cited UNITED STATES PATENTS 2,622,243 12/1952 Temple et al.89l X 3,283,657 11/1966 Kvavle 891 BENJAMIN R. PADGETT, PrimaryExaminer.

CARL D. QUARFORTH, Examiner.

S. I. LECHERT, JR., Assistant Examiner.

1. IN A PROCESS FOR DRIVING ANCHORING DEVICES BY A TOOL, THE STEPSCOMPRISING IGNITING A PROPELLANT COMPOSITION WHICH IS DEFLAGRATING ANDWHICH IS IN PELLET FORM TO DRIVE THE ANCHORING DEVICES, THE INGINITINGBEING OBTAINED BY PERCUSSION, THE PROPELLANT COMPOSISTION CONSISTINGESSENTIALLY OF A MIXTURE OF PENTAERYTHRITOL TETRANITRATE ANDTETRAZOLAZO-AMINO-GUANIDINE, THE LATTER BEING PREENT IN AN AMOUNTBETWEEN 5 AND 30% BY WEIGHT OF THE COMPOSITION.